The invention generally relates to an apparatus for heating the air/fuel mixture entering the cylinders of an internal combustion engine. More particularly, the invention relates to an electric heater having a one-piece housing adapted for mounting to the air intake system of an engine.
The air/fuel mixture entering the cylinders of an internal combustion engine is commonly heated to increase fuel economy and responsiveness to starting as well as to decrease pollutant discharge. One type of intake heating device generally includes a housing or frame disposed between a fuel delivery device and an air intake manifold. Another type of intake heating device is mounted within an open cavity of an intake manifold. After this second type of heating device is mounted on the intake, the heater and intake subassembly is subsequently mounted to an engine. In the aforementioned devices, current is passed through a heating coil or grid to increase the temperature of the surrounding air as it passes into a combustion chamber of the engine.
While the aforementioned heaters generally address cold starting and fuel economy issues, other concerns remain. For example, access to the prior art heaters is obtained only after the intake manifold is removed from the engine. Retro-fitting an existing vehicle not originally equipped with a heater is similarly difficult. In addition, prior art heaters have been specifically constructed to package within a given geometry and function only with a certain power system. As a result, many heater components were proliferated in order to meet varying customer needs. Furthermore, many prior heater designs exhibit unsatisfactory vibration resistance. These heaters may not continue to properly function after being fitting to a vehicle and subjected to repeated impact loading due to road inputs as the vehicle is used.
Accordingly, in view of the above concerns as well as the manufacturer's ever present desire to reduce manufacturing costs and complexity, a need exists for a robust air heater having a one-piece housing that may be installed within a vehicle intake air system without removing the intake manifold.